The way to stop the leakage of demos and unreleased music has always been to stop the people who leak it. And those people are neither YouTube personnel nor the fans -- those people are the ones who work with a musical act's publicists, producers, media, outside music or lyric writers, rehearsal and recording studios, and, uh, management. Madonna's people were particularly good at uploading her unreleased material, after which she'd step up and grab headlines by screaming bloody murder about being the victim of online piracy.